THE IMPORTANCE OF HEMATOCRIT IN THE INTERPRETATION OF COAGULATION TESTS IN THE FULL-TERM NEWBORN-INFANT

Background, Hematocrit (HCT) is significantly higher in newborns than in adults, but this fact is not usually considered when performing coa gulation tests in newborns. We studied 71 healthy full-term newborns a nd compared them to 100 healthy adults to test the hypothesis that cor recting the anticoagulant-to-blood ratio for neonatal HCT would reduce the differences among the two populations. Methods. PT, PTT, fibrinog en, platelets and factors II, VII, IX,X, V,VIII were measured in 71 he althy full-term newborns and 100 healthy adults. An anticoagulant-bloo d ratio corrected for HCT was used. In 16 newborns, a non corrected va lue was also used and results were compared with the corrected ratio. Results. A significant difference was observed between newborns and ad ults in all tests with the exceptions of fibrinogen and factor V. In t he 16 newborns from whom blood was collected without correcting in the anticoagulant, a significant difference was also found in all paramet ers but fibrinogen. A weak correlation linked the different variables. Conclusions. After correction for HCT, neonatal PT and factors V, VII , VIII and IX were much closer to adult values; neonatal PTT and facto rs II and X were still definitely lower.